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Shrinkage estimation usually reduces variance at the cost of bias. But when we care only about some parameters of a model, I show that we can reduce variance without incurring bias if we have additional information about the distribution of…

统计理论 · 数学 2017-11-01 Jann Spiess

Quantitative magnetic resonance imaging (qMRI) allows images to be compared across sites and time points, which is particularly important for assessing long-term conditions or for longitudinal studies. The multiparametric mapping (MPM)…

信号处理 · 电气工程与系统科学 2024-10-24 Klara Baś , Christian Lambert , John Ashburner

In this article we provide some nonnegative and positive estimators of the mean squared errors(MSEs) for shrinkage estimators of multivariate normal means. Proposed estimators are shown to improve on the uniformly minimum variance unbiased…

统计理论 · 数学 2007-10-08 Hisayuki Hara

Purpose: To develop neural network (NN)-based quantitative MRI parameter estimators with minimal bias and a variance close to the Cram\'er-Rao bound. Theory and Methods: We generalize the mean squared error loss to control the bias and…

医学物理 · 物理学 2024-05-07 Andrew Mao , Sebastian Flassbeck , Jakob Assländer

We conduct an asymptotic risk analysis of the nonlocal means image denoising algorithm for the Horizon class of images that are piecewise constant with a sharp edge discontinuity. We prove that the mean square risk of an optimally tuned…

统计理论 · 数学 2011-11-28 Arian Maleki , Manjari Narayan , Richard G. Baraniuk

We address the problem of image denoising in additive white noise without placing restrictive assumptions on its statistical distribution. In the recent literature, specific noise distributions have been considered and correspondingly,…

计算机视觉与模式识别 · 计算机科学 2015-01-28 Sagar Venkatesh Gubbi , Chandra Sekhar Seelamantula

In this paper, we consider the problem of estimating the density function of a Chi-squared variable on the basis of observations of another Chi-squared variable and a normal variable under the Kullback-Leibler divergence. We assume that…

统计理论 · 数学 2021-07-22 Yasuyuki Hamura , Tatsuya Kubokawa

We study shrinkage estimation of the mean parameters of a class of multivariate distributions for which the diagonal entries of the corresponding covariance matrix are certain quadratic functions of the mean parameter. This class of…

统计理论 · 数学 2022-07-04 Nikolas Siapoutis , Donald Richards , Bharath K. Sriperumbudur

The generic risk estimator addresses the problem of denoising images corrupted by additive white noise without placing any restriction on the statistical distribution of the noise. In this paper, we discuss an efficient FPGA implementation…

图像与视频处理 · 电气工程与系统科学 2023-01-13 Rinson Varghese , Chandrasekhar Seelamantula , Rathna G N , Ashutosh Gupta , Debajyoti Dhar

Wavelet shrinkage estimators are widely applied in several fields of science for denoising data in wavelet domain by reducing the magnitudes of empirical coefficients. In nonparametric regression problem, most of the shrinkage rules are…

统计方法学 · 统计学 2021-09-14 Alex Rodrigo dos Santos Sousa , Nancy Lopes Garcia

Learning from unlabeled and noisy data is one of the grand challenges of machine learning. As such, it has seen a flurry of research with new ideas proposed continuously. In this work, we revisit a classical idea: Stein's Unbiased Risk…

机器学习 · 统计学 2020-07-24 Christopher A. Metzler , Ali Mousavi , Reinhard Heckel , Richard G. Baraniuk

In this paper, we expand the theory of depth-unbiased source localization to unbiased parameter estimation and signal reconstruction of an arbitrary number of non-zero parameters to be recovered. The topic touches on the concept of exact…

信息论 · 计算机科学 2026-05-08 Joonas Lahtinen

The linear regression models are widely used statistical techniques in numerous practical applications. The standard regression model requires several assumptions about the regres- sors and the error term. The regression parameters are…

统计方法学 · 统计学 2016-10-23 P. Vellaisamy

We study the algorithmic problem of robust mean estimation of an identity covariance Gaussian in the presence of mean-shift contamination. In this contamination model, we are given a set of points in $\mathbb{R}^d$ generated i.i.d. via the…

数据结构与算法 · 计算机科学 2025-02-21 Ilias Diakonikolas , Giannis Iakovidis , Daniel M. Kane , Thanasis Pittas

In linear regression we wish to estimate the optimum linear least squares predictor for a distribution over $d$-dimensional input points and real-valued responses, based on a small sample. Under standard random design analysis, where the…

机器学习 · 统计学 2022-06-08 Michał Dereziński , Manfred K. Warmuth , Daniel Hsu

Penalized Least Squares are widely used in signal and image processing. Yet, it suffers from a major limitation since it requires fine-tuning of the regularization parameters. Under assumptions on the noise probability distribution,…

机器学习 · 统计学 2020-05-13 Barbara Pascal , Samuel Vaiter , Nelly Pustelnik , Patrice Abry

To recover a low rank structure from a noisy matrix, truncated singular value decomposition has been extensively used and studied. Recent studies suggested that the signal can be better estimated by shrinking the singular values. We pursue…

统计方法学 · 统计学 2014-11-25 Julie Josse , Sylvain Sardy

Unbiased estimators are introduced for averaged Bregman divergences which generalize Stein's Unbiased (Predictive) Risk Estimator, and the minimization of these estimators is proposed as a regularization parameter selection method for…

数值分析 · 数学 2021-11-22 Elias S. Helou , Sandra A. Santos , Lucas E. A. Simões

In this work, we propose a mean-squared error-based risk that enables the comparison and optimization of estimators of squared calibration errors in practical settings. Improving the calibration of classifiers is crucial for enhancing the…

机器学习 · 计算机科学 2025-02-24 Sebastian G. Gruber , Francis Bach

Neural networks are increasingly used to estimate parameters in quantitative MRI, in particular in magnetic resonance fingerprinting. Their advantages over the gold standard non-linear least square fitting are their superior speed and their…

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